We exploit rules of class formation to identify the causal effect of increasing the number of immigrants in a classroom on natives test scores, keeping class size constant (Pure Composition Effect). We explain why this is a relevant policy parameter although it has been neglected so far. We show...

Immigration is an important problem in many societies, and it has wide-ranging eects on the educational systems of host countries. There is a now a large empirical literature, but very little theoretical work on this topic. We introduce a model of family immigration in a framework where school...